The military uses shelter enclosures on vehicles such as HMMWVs for many different applications. One type of shelter is height reducible so that it can be driven on or off of a cargo plane (e.g., a C 130 cargo plane) without having to remove the shelter from the truck. The door of such an enclosure is 70″ inches off the ground. Therefore, some type of a ladder or stairway is required for easier access into the shelter. Also, in some configurations, a protective entrance is desired adjacent the door to the enclosure in case of a chemical attack. A platform is thus required for the protective entrance and a stairway or ladder is required to access the platform.
The design constraints for a platform and stairway or ladder are fairly severe. For example, the platform must fold up and be locked in place when the vehicle is driven away during road march. The platform must also fold open to allow for quick deployment. Hydraulic systems and the like are generally not favored since they add to the complexity, weight, and cost of the shelter system. Also, the ladder and platform or stairway cannot interfere with the raising and lowering of the top half of the shelter. A single person must be able to deploy and fold the platform down quickly and easily.
No known systems meet these requirements.